Method And Apparatus For Supplying A Gaseous Fuel To An Internal Combustion Engine

ABSTRACT

A method for supplying gaseous fuel from a tender car to an internal combustion engine on a locomotive comprising storing the gaseous fuel at a cryogenic temperature in a cryogenic storage tank on the tender car; pumping the gaseous fuel to a first pressure from the cryogenic storage tank; vaporizing the gaseous fuel at the first pressure; and conveying the vaporized gaseous fuel to the internal combustion engine; whereby a pressure of the vaporized gaseous fuel is within a range between 310 bar and 575 bar.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.14/311,321 filed Jun. 22, 2014, and a continuation of InternationalApplication No. PCT/CA2012/050931 having an international filing date ofDec. 21, 2012, entitled “Method And Apparatus For Supplying A GaseousFuel To An Internal Combustion Engine”. The '931 internationalapplication claimed priority benefits, in turn, from Canadian PatentApplication No. 2,762,697 filed on Dec. 22, 2011. The '931 internationalapplication is hereby incorporated by reference herein in its entirety.

FIELD OF THE INVENTION

The present application relates to supplying a gaseous fuel from a storeof the gaseous fuel on a tender car to an internal combustion engine ofa locomotive for combustion.

BACKGROUND OF THE INVENTION

Since the early 1980s several research projects and demonstrationprograms have attempted to employ natural gas as a fuel for locomotives.The initial motivation was to determine if any reduction in emissionlevels could be obtained compared to diesel locomotives, whilemaintaining the same level of power. These efforts were driven byevolving emission standards for locomotives from the EnvironmentProtection Agency (EPA), for which in 1997 the EPA established Tier 0, 1and 2 standards, and more recently in 2008 they set the Tier 3 and 4standards. Both the Tier 3 and 4 standards dramatically reduce emissionsof diesel particulate matter (PM) and nitrogen oxide (NOx). Out of theseefforts only one commercially available, proven and tested natural gasfuelled line-haul locomotive emerged, which employed a low pressureinjection technology. In a paper titled “An Evaluation of NaturalGas-fueled Locomotives”, published in November 2007 by BNSF RailwayCompany, Union Pacific Railroad Company (UPRR), the Association ofAmerican Railroads, (together known as the Railroads) and the CaliforniaEnvironmental Associates, the Railroads position on natural gas fuelledlocomotives was presented. Except for some potential niche applications,the Railroads did not believe there is an opportunity to use natural gasas a locomotive fuel to help meet emissions and performance goals. Thisposition was based on the one known commercially available natural gasfuelled line-haul locomotive available in North America. This productwas a conversion kit for the EMD 645 two-stroke diesel engine thatenables the locomotive to run on liquefied natural gas (LNG) as aprimary fuel, while employing diesel as a pilot fuel. The LNG fuel isvaporized and injected at low pressure (85-125 pounds per square inch(psi)) such that the fuel and air mix during compression. A smallportion of diesel “pilot” fuel is then injected into the cylinder at thetop of the stroke where it auto-ignites to facilitate combustion.

Several of the research projects and demonstration programs attemptedhigh pressure injection techniques where natural gas fuel was injectedlate in the compression cycle. In 1992 the UPRR began two of theseefforts in separate programs with Electro Motive Diesel (EMD) and GETransportation Systems (GE) to investigate the use of natural gas inline-haul, high-horsepower locomotive engines. This was a significant,multi-year effort in which UPRR expended over $15 million exploringbasic engine and fueling technology issues. The natural gas injectionpressures employed in both the EMD and GE systems were in the rangebetween 3000 psi and 4500 psi. Due to technical limitations, thelocomotives developed separately by EMD and GE were incapable of revenueoperation. The technical difficulties in both programs included failureof gas injectors, cryogenic LNG pumps for handling the cryogenic fuelbetween the tender tanks and the locomotives, the engine control systemsoftware, the gas transition control system software, and fuel systemjoint leaks.

The conversion kit for the EMD 645 developed out of a project started byBurlington Northern Railroad (BN) in 1987 involving a two pronged effortto develop natural gas fueling infrastructure and line-haul locomotivescapable of running on natural gas. For the fueling infrastructure, BNworked with Air Products and Chemicals (APC) to develop fuelinglocations and cryogenic tank equipped tender cars to support the use ofRefrigerated Liquid Methane (RLM), a high purity form of liquefiednatural gas, as a locomotive fuel. In a paper titled “LNG as a Fuel forRailroads: Assessment of Technology Status and Economics”, published bythe Gas Research Institute in January 1993, Bob Kirkland of APCindicates that LNG vaporization can be performed on the locomotive or onthe tender car. “As less energy is needed to pump a liquid than tocompress a gas, future tender car designs will likely deliver liquid toa pump located on the locomotive and upstream of the vaporizer. It wouldbe impractical, according to Bob Kirkland of Air Products, for thetender car to supply high pressure liquid to the locomotive. Such anarrangement would involve long lengths of high-pressure piping as wellas additional hardware between the locomotive and the tender car topower the pump.”

Based on the admissions of the Railroads and the results of the researchand demonstration projects cited above, it is evident that late cycle,high pressure direct injection of natural gas in a locomotive engine isnot a straightforward or obvious undertaking. Several technicalchallenges exist that have prevented a commercially available naturalgas locomotive line-haul product from emerging that can challenge andimprove upon the emissions from so called clean diesel locomotivetechnologies.

The present method and apparatus provide an improved technique forsupplying a gaseous fuel from a store of the gaseous fuel on a tendercar to an internal combustion engine of a locomotive for combustion.

SUMMARY OF THE INVENTION

An improved method of supplying gaseous fuel from a tender car to aninternal combustion engine on a locomotive comprising storing thegaseous fuel at a cryogenic temperature in a cryogenic storage tank onthe tender car; pumping the gaseous fuel to a first pressure from thecryogenic storage tank; vaporizing the gaseous fuel at the firstpressure; and conveying the vaporized gaseous fuel to the internalcombustion engine; whereby a pressure of the vaporized gaseous fuel iswithin a range between 310 bar and 575 bar. The gaseous fuel can benatural gas, methane or other hydrocarbon gaseous fuels. The method alsocomprises accumulating the vaporized gaseous fuel such that pressurefluctuations of the gaseous fuel due to changing operating conditions ofthe internal combustion engine are reduced. A mass flow rate of theinternal combustion engine is within a range of 7 kilograms/hour and 600kilograms/hour. The accumulation of the vaporized gaseous fuel is withina range of 50 liters and 200 liters. The method further comprisesreceiving advanced notice of upcoming changes in operating conditions ofthe internal combustion engine and doing at least one of proactivelypumping the gaseous fuel to increase the pressure of the vaporizedgaseous fuel, increasing a rate of pumping the gaseous fuel to increasethe pressure of the vaporized gaseous fuel, and decreasing a rate ofpumping the gaseous fuel to reduce pressure fluctuations above apredetermined pressure threshold. In the method waste heat from theinternal combustion engine can be transferred to the gaseous fuel at thefirst pressure such that the gaseous fuel vaporizes. The waste heat canbe transferred from engine coolant to a heat exchange fluid such thatthe heat exchange fluid transfers heat to the gaseous fuel at the firstpressure. The heat exchange fluid can be heated with a supplementaryheat source, which can be a gas boiler or an electric heater. When thesupplementary heat source is the gas boiler, the gas boiler generatesheat by combusting the gaseous fuel from the cryogenic storage tank, andthe gaseous fuel which is combusted can be vent gas. The method furthercomprises reducing conveyance of the vaporized gaseous to the internalcombustion engine in response to a decrease in the pressure of thevaporized gaseous fuel below a predetermined pressure threshold.

The method can further comprise delivering low pressure air from acompressed air supply on the locomotive to the tender car; pressurizingthe low pressure air to a high pressure; delivering the high pressureair to the locomotive; and forming a gaseous-fuel/air mixture by mixingthe vaporized gaseous fuel and the high pressure air on the locomotive.The gaseous-fuel/air mixture is directly introduced into combustionchambers in the internal combustion engine.

The vaporized gaseous fuel can be conveyed to the locomotive in the formof a gaseous-fuel/air mixture. The method further comprises deliveringlow pressure air from a compressed air supply on the locomotive to thetender car; pressurizing the low pressure air to a high pressure on thetender car; and forming the gaseous-fuel/air mixture by mixing thevaporized gaseous fuel and the high pressure air on the tender car. Thegaseous-fuel/air mixture is directly introduced into combustion chambersin the internal combustion engine.

The method can further comprise pressurizing low pressure air on thelocomotive to a high pressure; and forming a gaseous-fuel/air mixture bymixing the vaporized gaseous fuel and the high pressure air on thelocomotive. The gaseous-fuel/air mixture is directly introduced intocombustion chambers in the internal combustion engine.

An improved apparatus for supplying gaseous fuel from a tender car to aninternal combustion engine on a locomotive comprising a cryogenicstorage tank on said tender car for storing said gaseous fuel at acryogenic temperature; a first pump for pumping said gaseous fuel to afirst pressure from said cryogenic storage tank; a first heat exchangerfor vaporizing said gaseous fuel at said first pressure; a conduit forconveying said vaporized gaseous fuel from said first heat exchanger tosaid internal combustion engine; a pressure sensor operatively connectedwith said conduit for measuring a pressure of said vaporized gaseousfuel; and an cryogenic controller operatively connected with said firstpump and said pressure sensor and programmed to receive pressure signalsfrom said pressure sensor representative of said pressure of saidvaporized gaseous fuel and to operate said first pump to maintain saidpressure of said vaporized gaseous fuel within a range between 310 barand 575 bar. The conduit is sized such that it can accumulate vaporizedgaseous fuel within a range of 50 liters and 200 liters. Alternatively,an accumulator having a volume within a range of 50 liters and 200liters can be connected with the conduit for accumulating vaporizedgaseous fuel. There is an engine controller for controlling operation ofthe internal combustion engine. The engine controller is programmed totransmit advanced notice of changes in operating conditions of theinternal combustion engine to the cryogenic controller. In response tothe advanced notice the cryogenic controller is programmed to change astate of the first pump. The cryogenic controller operates the firstpump to increase the first pressure when the advanced notice comprisesan upcoming increase in mass flow rate of the vaporized gaseous fuel.The cryogenic controller operates the first pump to decrease a rate ofpumping when said advanced notice comprises an upcoming decrease in massflow rate of said vaporized gaseous fuel. There is a shut-off valveconnected between the first heat exchanger and the conduit. The shut-offvalve reduces and preferably prevents conveyance of the vaporizedgaseous fuel in the conduit when a pressure differential across theshut-off valve reaches a predetermined threshold. The apparatus furthercomprises a reservoir comprising a heat exchange fluid; a heat transferpump operatively connected with the reservoir to pump the heat exchangefluid; and a second heat exchanger receiving the heat exchange fluidunder pressure from the heat transfer pump and operative to transferwaste heat from a coolant of the internal combustion engine to the heatexchange fluid; such that the heat exchange fluid is circulated throughthe first exchanger for vaporizing the gaseous fuel at the firstpressure. There can be a supplementary heat source for heating the heatexchange fluid. The supplementary heat source can be a gas boiler or anelectric heater. The gas boiler generates heat by combusting the gaseousfuel from the cryogenic storage tank, and the gaseous fuel which iscombusted can be vent gas. There is also a transfer pump operative topump the gaseous fuel from the cryogenic storage tank to an intermediatepressure lower than the first pressure. The first pump is operative topump the gaseous fuel from the intermediate pressure to the firstpressure. The cryogenic storage tank can comprise a tank port and thetransfer pump comprises an inlet and an outlet. The transfer pump isdisposed in the tank port such that the inlet is inside the cryogenicstorage tank. In alternative embodiments the apparatus comprises asupplementary vessel connected with the cryogenic storage tank. Thesupplementary vessel comprises a tank port and the transfer pumpcomprises an inlet and an outlet. The transfer pump is disposed in thetank port such that the inlet is inside the supplementary vessel. Thegaseous fuel can be natural gas or methane.

The apparatus can comprise a supply of low pressure air located on thelocomotive. A multi-stage compression apparatus on the tender carpressurizes the low pressure air to a high pressure. A second conduitdelivers the low pressure air to the multi-stage compression apparatus.A mixing apparatus on the locomotive forms a gaseous-fuel/air mixture bymixing the high pressure air and the vaporized gaseous fuel. A thirdconduit delivers the high pressure air from the multi-stage compressionapparatus to the mixing apparatus. The gaseous-fuel/air mixture isdirectly introduced into combustion chambers of the internal combustionengine.

The vaporized gaseous fuel can be conveyed to the locomotive through theconduit in the form of a gaseous-fuel/air mixture. The apparatuscomprises a supply of low pressure air on the locomotive. A multi-stagecompression apparatus on the tender car pressurizes the low pressure airto a high pressure. A second conduit delivers the low pressure air tothe multi-stage compression apparatus. A mixing apparatus on the tendercar forms the gaseous-fuel/air mixture by mixing the high pressure airand the vaporized gaseous fuel. The gaseous-fuel/air mixture is directlyintroduced into combustion chambers of the internal combustion engine.

The apparatus can comprise a supply of low pressure air on thelocomotive. A multi-stage compression apparatus on the locomotivepressurizes the low pressure air to a high pressure. A mixing apparatuson the locomotive forms the gaseous-fuel/air mixture by mixing the highpressure air and the vaporized gaseous fuel. The gaseous-fuel/airmixture is directly introduced into combustion chambers of the internalcombustion engine.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of an apparatus for supplying gaseous fuel toan internal combustion engine according to one embodiment.

FIG. 2 is a pictorial view of a tender car according to the embodimentof FIG. 1;

FIG. 3 is a pictorial view of a tender car according to the embodimentof FIG. 1;

FIG. 4 is a pictorial view of a tender car according to the embodimentof FIG. 1;

FIG. 5 is a schematic view of an apparatus for supplying gaseous fuel toan internal combustion engine according to a second embodiment.

FIG. 6 is a schematic view of an apparatus for supplying gaseous fuel toan internal combustion engine according to a third embodiment.

FIG. 7 is a pictorial view of a tender car according to the embodimentof FIG. 1

FIG. 8A is a schematic view of an arrangement of a tender car and twolocomotives.

FIG. 8B is a schematic view of an arrangement of a tender car and threelocomotives.

FIG. 8C is a schematic view of an arrangement of three tender cars andthree locomotives.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT(S)

Referring to FIG. 1, fuel apparatus 10 is shown for supplying a gaseousfuel from tender car 20 to internal combustion engine 30 on locomotive40. Tender car 20 supplies gaseous fuel for combustion in engine 30 andis connected with and hauled by locomotive 40. Cryogenic storage tank 50is an ISO tank that stores the gaseous fuel at cryogenic temperatures ina liquid phase. As used herein, a gaseous fuel is any fuel that is in agaseous phase at standard temperature and pressure. The gaseous fuel intank 50 is LNG in the present example, but in other embodiments thegaseous fuel can refrigerated liquid methane (RLM) or other hydrocarbonfuels. Tank 50 is securely connected with tender car 20 when supplyinggaseous fuel for engine 30, and is also detachable such that an emptytank on the tender car can be replaced with a full tank. Tank 50comprises a fill receptacle and a pressure relief valve to releasepressure inside the tank when it builds up beyond predeterminedacceptable levels. Cryogenic electronic controller 140 communicates withtank 50 to receive information related to a quantity of LNG remaining inthe tank, and this information can comprise a level of LNG in the tank,vapor pressure within the tank, and a temperature of LNG within thetank. In the present example cryogenic controller 140 is a computercomprising a processor and memories, including a permanent memory, suchas FLASH or EEPROM, and a temporary memory, such as SRAM or DRAM, forstoring and executing a program.

Low pressure liquid fuel pump 60 transfers LNG at low pressure from tank50 to high pressure liquid fuel pump 70 in high pressure gas supplysystem 80. As used herein, gas refers to gaseous fuel. Low pressure pump60 is shown located between tank 50 and high pressure pump 70 in thepresent example. In other embodiments pump 60 can be located completelywithin tank 50 or in a tank port such that an inlet of the pump isdisposed inside the tank and an outlet is disposed outside the tank. Thetank port can also be provided in a secondary vessel connected with tank50. The secondary vessel couples tank 50 to pump 60 such that thesecondary vessel is flooded with LNG from tank 60 and the inlet of thepump is immersed in the LNG in the secondary vessel. It is advantageousto locate low pressure pump 60 such that it can be efficientlymaintained at an operational temperature and can be convenientlyaccessed for maintenance. The operational temperature for pump 60 isclose to the boiling temperature of the cryogenic fluid (LNG) such thatthe fluid does not vaporize in the pump while being pressurized from theinlet to the outlet. In light of the desired advantages the preferredlocation for pump 60 is in the tank port. However, other factors such asinteroperability with existing ISO tanks may require placement of pump60 in the other locations. In other embodiments, pump 60 and thesecondary vessel can be located on high pressure gas supply system 80.In yet other embodiments pump 60 may not be required such that pump 70receives LNG directly from tank 50. In still further embodiments, pump70 can be located within another secondary vessel which is flooded withLNG either directly from tank 50 or from pump 60.

High pressure pump 70 pressurizes the LNG from low pressure pump 60 andsupplies pressurized liquid fuel to heat exchanger 90 which vaporizesthe LNG into a gaseous phase. The gaseous fuel is conveyed from heatexchanger 90 to engine 30 through conduit 100, solenoid valve 110 andconduit 120. Cryogenic controller 140 communicates with pressure sensor150 to receive information related to the pressure of the gaseous fuelin conduit 120 and commands pumps 60 and 70 to operate in order tomaintain a predetermined pressure threshold in conduit 120. The pressureof the gaseous fuel in conduit 120 is maintained between a range of 310bar (˜4500 psi) and 575 bar (˜8340 psi) which covers a range ofinjection pressures for direct fuel injectors (not shown) in engine 30.Injection pressure within this range allows sufficient mass flow rate ofgaseous fuel to meet full load operating requirements for engine 30. Inaddition, as the injection pressure is increased there is a reduction inemissions, and especially in particular matter (PM).

Valve 110 is commanded by controller 140 to open and close dependingupon operating and fault conditions to allow or prevent gaseous fuelfrom entering conduit 120. Valve 110 also operates as an automaticshutoff valve that automatically closes (without command from controller140) when the pressure differential across an inlet and an outlet ofvalve 110 reaches a predetermined magnitude such that conveyance of thegaseous fuel in conduit 120 is reduced, minimized or preferably stopped.This is advantageous in the situation when the tender car 20 accidentlybreaks away from locomotive 40 while conduit 120 is connectedtherebetween, in which case the pressure in conduit 120 will suddenlydecrease whereby the pressure differential across valve 110 willincrease above the predetermined magnitude. In other embodiments valve110 can be two valves where one valve is commanded by controller 140 toopen and close, and the other valve automatically closes based on theinlet-to-outlet pressure differential.

There are other valves (not shown) on tender car 20 that are actuated bycompressed air. A compressed air supply (not shown) can be located onlocomotive 40, on tender car 20 or in high pressure gaseous fuel system80. The solenoid of valve 110 can actuate a valve that controls the flowof gaseous fuel directly, or it can actuate a valve that controls theflow of compressed air to another valve that controls the flow ofgaseous fuel.

The compressed air supply can be employed for enriching gaseous fuelbefore it is directly introduced into combustion chambers in engine 30on locomotive 40. The gaseous-fuel/air mixture provides an increasedequivalence ratio in fuel jets in the combustion chambers of engine 30resulting in improved combustion characteristics and reduced emissions.There are various techniques for providing a gaseous-fuel/air mixture,such as disclosed in the Applicant's co-pending Canadian PatentApplication titled “Air-Enriched Gaseous Fuel Direct Injection For AnInternal Combustion Engine”, filed on Dec. 17, 2012, which isincorporated by reference herein in its entirety. In one such technique,air from the compressed air supply on locomotive 40 is furthercompressed in a multi-stage compression apparatus on the locomotive to ahigh pressure. Air from the compressed air supply is approximately 6 barand can be considered low pressure air. High pressure air frommulti-stage compression apparatus is in the range of 155 bar to 575 bardepending upon the technique of mixing air with gaseous fuel and therequired injection pressure of the gaseous-fuel/air mixture. Highpressure air is mixed with gaseous fuel from conduit 120 in a mixingapparatus on locomotive 40, and the gaseous-fuel/air mixture isintroduced directly into combustion chambers of engine 30. In anothertechnique, air from the compressed air supply on locomotive 40 isdelivered to the multi-stage compression apparatus that is now locatedin high pressure gas supply system 80 on tender car 20. The multi-stagecompression apparatus pressurizes air to the high pressure. In thistechnique, the mixing apparatus can be located in supply system 80 suchthat the gaseous-fuel/air mixture is delivered to locomotive 40 overconduit 120, or can be located on locomotive 40 as in the previoustechnique such that conduit 120 delivers gaseous fuel and anotherconduit delivers high pressure air to the mixing apparatus on locomotive40.

The maximum mass flow rate requirement for engine 30 operating at fullload is very large, for example around 600 kg/hr. In contrast the idlingflow rate requirement for engine 30 is substantially reduced, forexample around 7 kg/hr. Depending upon operating conditions, theinstantaneous mass flow rate can vary dramatically between the maximumand idling flow rate requirements. In order to avoid excessive pressurefluctuations in conduit 120, which lead to a reduction in combustionperformance and in engine operating stability, accumulator 130 isconnected with conduit 100 and acts as a gas buffer that filterspressure fluctuations that occur when instantaneous flow raterequirements for engine 30 change. Based on the mass flow raterequirements for engine 30, accumulator 130 comprises a gas buffervolume within a range of 50 liters and 200 liters. In other embodimentsaccumulator 130 can be replaced by sizing conduit 100 and/or conduit 120accordingly.

Returning to heat exchanger 90, its operation will now be furtherdescribed. Reservoir 160 comprises heat exchange fluid, for exampleglycol, that circulates in heat exchanger 90 to vaporize the LNG. Theheat exchange fluid is transferred through heat exchanger 170 by heattransfer pump 180 such that waste heat in coolant from engine 30increases its temperature. The coolant from engine 30 is conveyed overconduit 190 and circulates in heat exchanger 170 from which it returnsto the engine. The heat exchange fluid is conveyed over conduit 200 tohigh pressure gas supply system 80, where it circulates through heatexchanger 90 and transfers heat to and vaporizes the LNG. Depending uponhow the instantaneous mass flow rate for engine 30 changes based onvarying operating conditions, there may not be enough waste heat fromengine 30 to meet the vaporization load in heat exchanger 90. In thissituation, supplementary heat exchange system 210 can increase thetemperature of the heat exchange fluid in conduit 200 before itcirculates in heat exchanger 90. System 210 comprises a gas boiler withan isolated combustion air intake and discharge (similar to a sealedcombustion residential gas fireplace or industrial radiant heater) thatburns gaseous fuel in conduit 220 from tank 50. Conduit 220 conveys ventgas and/or gas vapor from within tank 50 to heat exchange system 210.The heat exchange fluid from conduit 200 is circulated through heatexchange system 210, where its temperature can be increased, andtransferred over conduit 230 to heat exchanger 90, from which it returnsto reservoir 160 over a return conduit (not shown). Heat transfer pump180 pressurizes the heat exchange fluid to enable its circulation asdescribed above. As would be understood by those familiar with thetechnology involved here, heat transfer pump 180 can be located atalternative locations in the above described arrangement of componentsas illustrated in FIG. 1 that achieve the same result, and suchalternative locations are considered within the scope the presentdisclosure. Similarly, reservoir 160 can be located on locomotive 40,tender car 20 and within high pressure gas supply system 80.

Gas vent system 310 comprises a burner and a low pressure gasaccumulator with an outlet regulator. The accumulator captures gasvented from tank 50. Captured gas is flow regulated to the burner toreduce Greenhouse gas emissions. Heat exchange system 210 can beemployed to burn gas captured by gas vent system 310.

Conduits 120 and 200 provide a quick connect and disconnect feature thatenables these conduits to non-destructively divide into two parts eachsuch that locomotive 40 and tender car 20 can move apart from eachother. Shut-off valve 110 blocks the flow of gaseous fuel when conduit120 divides into two parts in the event of an accidental break-awaybetween locomotive 40 and tender car 20. A shut-off valve can also beprovided on locomotive 40 to prevent the heat exchange fluid fromspilling out when conduit 200 divides into two parts. As an alternativeconduit 200 can comprise a self-closing disconnect which closes whenconduit 200 disconnects into two parts, and opens when conduit 200 isconnected into one part.

Cryogenic controller 140 communicates with engine electronic controller240 to receive a feed forward parameter representative of gas demandfrom engine 30 and to transmit meaningful fault information to enableintelligent decision making on engine 30 if fuel supply is notsufficient for desired operating point. Engine controller 240 is acomputer comprising a processor and memories, including a permanentmemory, such as FLASH or EEPROM, and a temporary memory, such as SRAM orDRAM, for storing and executing a program. Engine controller 240commands the direct fuel injectors to open and close valves therein toinject gaseous fuel into cylinders (not shown) in engine 30 and receivessignals from sensors (not shown) that monitor operational parameters ofthe engine. Controller 240 is also responsive to command signals from alocomotive operator communicated by locomotive electronic controller 270to change the current operating state of engine 30. In response to thesensor signals and the command signals, engine controller 240 informscryogenic controller 140 of an upcoming change in the quantity ofgaseous fuel that will be injected into the cylinders in engine 30 and acorresponding change in the instantaneous mass flow through conduit 120.In response to this advance notice, cryogenic controller 140 can takeproactive measures to prepare for the upcoming change by adjusting thecurrent state of pumps 60 and 70. For example, in response to anupcoming increase in the mass flow rate in conduit 120 controller 140can proactively begin to operate pumps 60 and/or 70, or increase a rateof pumping by increasing the operating speed of pumps 60 and/or 70 ifthey are already operating, to increase the pressure in conduit 120 suchthat an undershoot pressure fluctuation below a predetermined lowerpressure threshold is reduced, minimized or preferably prevented.Similarly, in response to an upcoming decrease in the mass flow rate inconduit 120 controller 140 can proactively begin decreasing the rate ofpumping by decreasing the operating speed of pumps 60 and 70 such thatan overshoot pressure fluctuation above a predetermined upper pressurethreshold is reduced, minimized or preferably prevented. Cryogeniccontroller 140 also communicates with telemetry module 320 and informsthe telemetry module, engine controller 240 and locomotive controller270 of faults detected in the components it communicates with, andwhether any operational parameters monitored by it are not withinpredetermined ranges or compliant with predetermined thresholds.Telemetry module 320 communicates wirelessly with a locomotive commandcenter and transmits the data it receives from controller 140, such astank pressure, tank level and tender car diagnostics. Locomotivecontroller 270 is a computer comprising a processor and memories,including a permanent memory, such as FLASH or EEPROM, and a temporarymemory, such as SRAM or DRAM, for storing and executing a program.

Referring to FIG. 2, tender car 20 further comprises flat car 280 onwhich cryogenic storage tank 50 and high pressure gaseous fuel supplysystem 80 are mounted. In FIG. 3, tender car 20 comprises two storagetanks 50 and two supply systems 80, one for a locomotive at either endof well car 281. In other embodiments there can one storage tank 50 andone supply system 80 associated with well car 281. In the embodiment ofFIG. 7, both storage tank 50 and supply system 80 are located within thewell of well car 281. FIG. 4 illustrates cryogenic rail tank car 300that has been modified to accommodate high pressure gas supply system80. Cryogenic rail tank car 300 is conventionally employed to haulcryogenic fluids, and in FIG. 4 it is shown adapted to act as the tendercar for locomotive 40. As depicted in FIG. 4, key interface pointsbetween the three main subsystems comprise rail car chassis 290,cryogenic storage tank 51 and high pressure gaseous fuel supply system80. In other embodiments rail car chassis comprises a support extendingunderneath and supporting storage tank 51. Referring now to FIGS. 8A, 8Band 8C, there are shown examples of advantageous combinations of tendercar(s) 20 and locomotive(s) 40 that employ one or more high pressure gassupply systems 80. In these examples, the tender cars can be the onesshown in FIGS. 2, 3, 4 and 7. In FIG. 8A, one tender car 20 suppliesgaseous fuel for two locomotives 40 located at opposite ends of thetender car. In FIG. 8B, one tender car 20 supplies gaseous fuel forthree locomotives 40 located in sequential order adjacent one end of thetender car. In FIG. 8C, three tender cars 20 arranged in sequentialorder supply gaseous fuel for three locomotives 40 also arranged insequential order adjacent the tender cars. There are other advantageouscombinations of tender cars 20 and locomotives 40.

With reference to the schematic view of FIG. 5, there is shown a secondembodiment of fuel apparatus 10 that is similar to the embodiment ofFIG. 1 and like parts have like reference numerals and are not describedin detail, if at all. Heat exchange system 211 comprises an electricheater (not shown) that receives electrical power from electricgenerator 240 over conduit 250. Similar to heat exchange system 210,depending upon the current operating state and operating history ofengine 30, the electric heater in system 211 can increase thetemperature of the heat exchange fluid in conduit 200 before the fluidis circulated in heat exchanger 90. In other embodiments heat exchangesystem 211 can be located on locomotive 40.

With reference to the schematic view of FIG. 6, there is shown a thirdembodiment of fuel apparatus 10 that is similar to the embodiment ofFIG. 1 and like parts have like reference numerals and are not describedin detail, if at all. High pressure gas supply system 80 is located onlocomotive 40. This is advantageous since conduit 260 between pumps 60and 70, which now runs between tender car 20 and locomotive 40, is at alow pressure which reduces the length of high pressure conduit overall.A similar modification to the embodiment of FIG. 5 can be made.

While particular elements, embodiments and applications of the presentinvention have been shown and described, it will be understood, that theinvention is not limited thereto since modifications can be made bythose skilled in the art without departing from the scope of the presentdisclosure, particularly in light of the foregoing teachings.

What is claimed is:
 1. A method of supplying gaseous fuel from a tendercar to an internal combustion engine on a locomotive comprising: storingsaid gaseous fuel at a cryogenic temperature in a cryogenic storage tankon said tender car; pumping said gaseous fuel to a first pressure fromsaid cryogenic storage tank; vaporizing said gaseous fuel at said firstpressure; and conveying said vaporized gaseous fuel to said internalcombustion engine; whereby a pressure of said vaporized gaseous fuel iswithin a range between 310 bar and 575 bar.
 2. The method of claim 1,further comprising accumulating said vaporized gaseous fuel wherebypressure fluctuations of said gaseous fuel due to changing operatingconditions of said internal combustion engine are reduced.
 3. The methodof claim 2, wherein a mass flow rate of said internal combustion engineis within a range of 7 kilograms/hour and 600 kilograms/hour, and saidaccumulation of said vaporized gaseous fuel is within a range of 50liters and 200 liters.
 4. The method of claim 1, further comprisingreceiving advanced notice of upcoming changes in operating conditions ofsaid internal combustion engine and proactively pumping said gaseousfuel to increase said pressure of said vaporized gaseous fuel.
 5. Themethod of claim 1, further comprising receiving advanced notice ofupcoming changes in operating conditions of said internal combustionengine and increasing a rate of pumping said gaseous fuel to increasesaid pressure of said vaporized gaseous fuel.
 6. The method of claim 1,further comprising receiving advanced notice of upcoming changes inoperating conditions of said internal combustion engine and decreasing arate of pumping said gaseous fuel to reduce pressure fluctuations abovea predetermined pressure threshold.
 7. The method of claim 1, furthercomprising transferring waste heat from said internal combustion engineto said gaseous fuel at said first pressure whereby said gaseous fuelvaporizes.
 8. The method of claim 7, wherein said waste heat istransferred from an engine coolant to a heat exchange fluid, and saidheat exchange fluid transfers heat to said gaseous fuel at said firstpressure.
 9. The method of claim 8, further comprising heating said heatexchange fluid with a supplementary heat source.
 10. The method of claim9, wherein said supplementary heat source is one of a gas boiler and anelectric heater.
 11. The method of claim 10, wherein when saidsupplementary heat source is said gas boiler, said gas boiler generatesheat by combusting said gaseous fuel from said cryogenic storage tank.12. The method of claim 11, wherein said gaseous fuel is vent gas fromsaid cryogenic storage tank.
 13. The method of claim 1, furthercomprising reducing conveyance of said vaporized gaseous to saidinternal combustion engine in response to a decrease in said pressure ofsaid vaporized gaseous fuel below a predetermined pressure threshold.14. The method of claim 1, wherein said gaseous fuel is natural gas. 15.The method of claim 1, further comprising: delivering low pressure airfrom a compressed air supply on said locomotive to said tender car;pressurizing said low pressure air to a high pressure; delivering saidhigh pressure air to said locomotive; and forming a gaseous-fuel/airmixture by mixing said vaporized gaseous fuel and said high pressure airon said locomotive.
 16. The method of claim 15, wherein saidgaseous-fuel/air mixture is directly introduced into combustion chambersin said internal combustion engine.
 17. The method of claim 1, whereinsaid vaporized gaseous fuel is conveyed to said locomotive in the formof a gaseous-fuel/air mixture, the method further comprising: deliveringlow pressure air from a compressed air supply on said locomotive to saidtender car; pressurizing said low pressure air to a high pressure onsaid tender car; and forming said gaseous-fuel/air mixture by mixingsaid vaporized gaseous fuel and said high pressure air on said tendercar.
 18. The method of claim 15, wherein said gaseous-fuel/air mixtureis directly introduced into combustion chambers in said internalcombustion engine.
 19. The method of claim 1, further comprising:pressurizing low pressure air on said locomotive to a high pressure; andforming a gaseous-fuel/air mixture by mixing said vaporized gaseous fueland said high pressure air on said locomotive.
 20. The method of claim19, wherein said gaseous-fuel/air mixture is directly introduced intocombustion chambers in said internal combustion engine.